How is material dependent damping (MP,DAMP) used in a psd analysis?
In a spectrum analysis, material dependent damping is treated as a ratio to critical for each material. Note that the damping must be specified in the modal and element results must be expanded. Here is a test which shows how small values of damping change the psd results. The psd response does vary inversely when damping is changed from .01 to .005. /prep7 /title,Role of MP,DAMP in a PSD analysis et,1,63 r,1,.1 mp,ex,1,28e6 mp,dens,1,0.0007 mp,damp,1,.005 ! material dependent damping rect,,10,,1 esize,1 amesh,1 nsel,s,loc,x,0 d,all,all nsel,all fini /solu antype,modal, modopt,lanb,1 mxpand,1,,,yes solve fini /solu antype,spectrum spopt,psd,10,on psduni,1,accg psdfrq,1,,10,100,1000,1100 psdval,1,.6,.7,1,.1 psdres,disp,abs psdres,acel,abs nsel,s,loc,x,0 d,all,uz,1 nsel,all outpr,nsol,1 pfact,1,base psdcom solve fini /post1 set,list set,3,1 prns,u |
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